It is recognized that, in addition to its light emitting mode, a LED can be set to a light sensing mode where it senses incident light and responds by generating a current. This function has been employed in lighting applications for remotely controlling a luminaire to switch on/off. Primarily, all that it takes is to periodically set the LED in the light sensing mode during a short interval, and to perform a threshold detection of the current generated by the LED during that interval. By illuminating the LED a current above the threshold will be detected and the LED will be switched on if it is off. By illuminating the LED a second time it will be switched off, etc.
For convenient user interaction offering more complex possibilities of for example dimming, colour tunability, etc., a simple on/off switching is not enough. Existing solutions use for example an RF-based remote control with a receiver structure integrated in the luminaire, together with a driver with enhanced functionality. A recent example is a “LivingColors LED lamp”, by Philips.
However, since OLEDs for lighting applications can be manufactured to have extreme properties, such as a particularly small thickness, or transparency, a number of new and unique applications are reachable, which would make the above-mentioned receiver structure inconvenient or even prevent some applications.